There are a few different ways that you can approach this, and I've covered them in more detail in a post on dropping pumping sessions. (exclusivepumping.com)
I talked about it in more detail in my post on the autoimmune protocol introduction and then again in the one about all disease beginning in the gut. (joannafrankham.com)
There are many reasons why the offline method is the best (and safest), this is discussed in much more detail in our post here. (blokt.com)